A multi-machine study of the interaction between locked modes and plasma rotation

In tokamaks, tearing modes, a class of magneto-hydro-dynamic instabilities, can interact with the passive structures, inducing eddy currents which slow down the plasma rotation. When the rotation velocity is reduced to a critical value, the magnetic island associated to the mode locks and grows up to large amplitudes, leading often to a disruption. A reduced plasma flow also implies the loss of the beneficial roles of plasma rotation, such as the reduction or suppression of both MHD and turbulent instabilities. Locked modes (LMs) can also be induced by applying magnetic field perturbations (MPs). The objectives of this work are to investigate the rotation braking caused by the LM presence and to assess the role of the plasma density in the evolution of the rotation profile, through the analysis of JET, MAST-U and ASDEX Upgrade datasets.